1. Field of the Invention
The present invention relates to a nuclear energy installation having a gas-cooled reactor core, and with at least two parallel guided cooling gas circuits which are connected to the reactor core and which have components for the discharge of the energy of the cooling gas whereby, preceding the inlet of the cooling gas into the reactor core which has been cooled in the cooling gas circuit, the socalled cold gas and/or subsequent to the exit of the cooling gas from the reactor core, gas which has been heated in the reactor core, the so-called hot gas, there is presently provided at least one gas collecting chamber in which there terminate the gas conduits and/or the gas distributors of the cooling gas circuits.
In gas-cooled nuclear energy installations it is necessary that there be met safety precautions, particularly in the instance of a gas conduit rupture. The effects of such a rupture and the resultant damagaes must be confined to a minimum extent. The nuclear energy installations encompass reactor pressure vessels which are formed of steel or of prestressed concrete and which are designed, under consideration of the maximum expected pressures within the space encompassed thereby. Additionally, it is necessary that there be avoided a destruction of gas conduits and components which are adjacent to the bursting gas conduit, through a fragmentation effect (German Patent Specification No. 2,435,358).
However, above all, care must be exercised that, as a result of the sudden pressure reduction in the gas circuit, there be maintained the operational ability of cooling installations which serve for after heat removal, so as to prevent the consequence of a possible destruction of the reactor core.
2. Discussion of the Prior Art
In order to slow down the speed of the pressure drop-off in the cooling gas circuits upon the bursting of one of the gas conduits, it is known to insert flow restrictors into the gas conduits. Thus, for example, in boiling water reactors there are utilized Venturi nozzles. However, disadvantageously there is caused a pressure loss during normal operation due to the interposition of these nozzles. In order to avoid this disadvantage, it has become known from German Laid-Open Patent Specification No. 2,249,690 to provide a safety rupture location (Sollbruchstelle) in the pressure-supporting wall structure of the gas conduit, and to insert within the gas conduit a member of smaller cross-section at this location which, upon rupture of the gas conduit, reduces the outlet cross-section available to the cooling gas. The abovementioned measures are, however, relatively complex. In reactor installations which include a plurality of parallel guided cooling gas circuits which are connected to the reactor core, which are known under the designation of a nuclear reactor installation in a multi-loop construction, compare Jul-Bericht, Jul-941 RG, April 1973, one proceeds from the position that, due to the distribution of the cooling gas flow into a plurality of cooling gas circuits, a limitation of the consequent effects upon the rupture of a gas conduit has already been attained because the individual gas conduits convey lesser flow quantities and are dimensioned smaller and, as a result thereof, one must calculate with lower speeds in the pressure drop-off in the overall system. Nevertheless, it is disadvantageous that, upon the rupture of a gas conduit, the hereby generated expansion wave in the regions of the nuclear energy installation in which the gas conduits of the individual cooling gas circuits are joined together or branched, penetrates into the still intact regions of the nuclear energy installation and, through destruction of further installation components, endangers their operational abilities, in particular the operational ability of the after heat removal system. But, even when the after heat removal system remains undisturbed, after the commencement of the operation of the after heat removal system there cannot be avoided shortcircuiting flows of the cooling gas, so that the after heat which develops in the reactor core cannot be withdrawn in a desired manner.